Well there's a couple of things going on here. First, it doesn't matter what the displacement is if you bore the engine .3 over because you have ruined the block!! Boring is done in hundredths of an inch so the question should be about boring 0.030". That extra zero between the decimal point and the 3 makes a big difference.
*rolls eyes*
You knew what I meant
Gosh, I'm sorry that I lack the clairvouyant ability to properly identify your automotive knowledge when you ask such a basic question. Your mistake is a common one and I thought it may be beneficial to clarify the point, if not for your benefit, then for the benefit of a real newbie who may be reading the thread. Other common mistakes are asking about a V6 and a "posi" rearend in a classic mustang.
Its not the lack of "clairvouyant abilty" that was the problem. It was the condesending sarcasm.
Seek and ye shall receive. The sarcasm came in with the rolling eyes. My original post just stated a fact. If you do not want scarism, do not invite it.
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In fairness we should all agee that it is easy to misplace the decimal point when we are talking about "30 over" cylinders/pistons.
When we use the above terminology, it is a simple mental slip to misplace the decimal place, it is almost like a mental trick. I have done so myself...I think even on this forum, even though I know better!
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66 Coupe I-6 Conversion, 408 Windsor, Tremec TKO 600 Wilwood fronts, SSBC Rears 9" Track Loc.
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Back to an older post(s):
quote:
ORIGINAL: JMD
quote:
ORIGINAL: Soaring
I suck at math. 292 and change sounds about right, but how does that affect the horsepower? OK math gurus. You have gone from 289 cubic inches to 292 by boring 0.030 over. Now, how much horsepower have you added to that engine if any? Show each step of the math.
292.87 divided by 288.52 = 1.015% increase in displacement, assuming 300 HP with standard bore = 304.5 HP assuming all efficiency issues remain constant, and proportional increase in power,,, ... so 4.5 HP???
JMD - I know you stated the assumption of "proportional increase in power" in your calculations, but I think you're on to a great philosophical question...
Basically, boring increases the volume but keeps the stroke unchanged. I think with your statement above, we would have to assume that the stoke would also increase 1.015% to remain "linear" in the increase.
Oh this is dizzying me up already... Forget I even brought it up!
No, I am not going to lock it because the sane ones on here are giving a good education. What I will do though is delete any and all of the threads you and highheeler type that are not on topic. Now, knock off the flaming and get back to talking about the subject.
Mine is as long as I mention: You should have your crank offset ground whenever it needs machining. It's the same price, adds cubes, adds CR, etc. Though it isn't worth taking down an engine to do this, it's worth while for most rebuilds.
No, I am not going to lock it because the sane ones on here are giving a good education. What I will do though is delete any and all of the threads you and highheeler type that are not on topic. Now, knock off the flaming and get back to talking about the subject.
Go Glen FTW!!! You guys crack me up!
Do I dare ask (since I don't know the bore & stroke) what is the displacement of a 351 that is bored .030 over???
Just kidding... really - just kiding...
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Daily driver with a 351W, T5, 3.55, 3G, R&P and other ridiculously described mods that only we can understand…
No, I am not going to lock it because the sane ones on here are giving a good education. What I will do though is delete any and all of the threads you and highheeler type that are not on topic. Now, knock off the flaming and get back to talking about the subject.
Go Glen FTW!!! You guys crack me up!
Do I dare ask (since I don't know the bore & stroke) what is the displacement of a 351 that is bored .030 over???
Just kidding... really - just kiding...
Actually, not me, I'd like to know. If for no other reason, to irritate! Just kidding.
What is it? and can you do it safely? Thanks
< Message edited by 65Raven65 -- 6/22/2007 1:30:37 AM >
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for the record, oem replacement pistons in oversize are destroked so that they keep the compression from getting bumped up and keep them down in the hole if the block was resurfaced. the increase in displacement should add a few pones (and no, the stroke would not have to increase.... its the overall displacement increase that nets the hp gains) BUT because rebuilder pistons will keep your compression from bumping or possibly even LOWER our compression, most likey that 4.5 hp will never be seen - although the freshness of the motor may make it seem like you have a hp jump. lastly, offset grinding isnt really a possibility when a stock crank is getting reground. even at a .010 / .010 grind they are only taking .005 off each side of the journal and thats about what it takes to clean a crank up. heck, many times even that is not enough which is why .020 cranks are a common sight (of course some may have been .010 cranks in a past life already)
How do you change the stroke with the piston? Isn't the stroke determined by the crank? I could see raising the rod pins on the piston to account for decking the block, but wouldn't that leave the stroke the same?
Printable Version
RE: What the cubic inches on a .30 over 289? - 
292 and change sounds about right, but how does that affect the horsepower? OK math gurus. You have gone from 289 cubic inches to 292 by boring 0.030 over. Now, how much horsepower have you added to that engine if any? Show each step of the math. 
